US2478414A

US2478414A - Breakdown testing apparatus

Info

Publication number: US2478414A
Application number: US517352A
Authority: US
Inventors: Leon V Michal
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1944-01-07
Filing date: 1944-01-07
Publication date: 1949-08-09
Anticipated expiration: 1966-08-09

Description

-Aug.. 9, 1949. v. MICHAL BREAKDOWN TESTING APPARATUS Filed Jan. 7, 1944 2 sheets-sheet 1 M/l/FA MR i. M M/CWAL By /AM K W ATTO/PA/fy 1949. v. MICHAL BREAKDOWN TESTING APPARATUS 2 Sheets-Sheet 2 Filed Jan. 7, 1944 Patented Aug. 9, 1949 TESTING APPARATUS Loon: V. Michal, Chicago, Ill.,.a,ssignoi: to Western; Electric Company, Incorporated; New York. N..Y.,,.a corporation of New York Application January 7, 1944;.Serial1 Nm75352 4 claims. (Cl. 115-183) This: invention. reiatos to: breakdown. testing apparatus, and; more: pantimrlarly' to; apparatus for dielectric: laminations fin? breakdown.

In isam obziect ofi the: present. invention: to pro:-- vidn a; simple and accurate apparatus, for rapidly making, breakdown tests,

In accordance: with. one embodiment: of the: inmention: an; appiiedi to; the: of! a breakdown test: on mica; larninavtionshaving: silver sheets applied to-opnnsite: faces: thereof, a: plurality of laminationsi placed: inv a; rack or cradle; which may then be slipped into a testing fixtureshaving spring-r contacts to bieam against: a: conducting member: commonitotall; emigrant-merits dmtherack or; cradles Afiter'ttm rack: cradiezhasz beam thus positionen in the: fixture, ahingedtbraokeh sup norm or number-'01; noun; lamps onion-1- in number to; the number of compartments the cradle mar; be: rushed to cazrm spring contacts fi'HgBIS innividuaiz to; that lamps into contact with; a2 surfia'oe 01f the laminwtionsi The: neon; lamps: are coruzrecteddnpaxaiini: 1703-13119: output an a: higirvo1trig-e transformer amt; are: each in. senias with av relatively nesisfianc g. Hart: of which shunted by the-nnmlmnwhenehyrwhmmbreab dimn occurs. in: one of the its associnted lamps wiiia bot will notinterfere with the other test circuits: 11315311211 with;

comnleize understanding: ot the: invention had by? reference to the fioiinwing dataiiem die:-

scription when cons-inched? in. conjunction; with the am drawings, wherem 11 at sidn eiemtionak view 05 apparatus". comprising. at. plfdfiiiflifidl embodiment of: the; in.- ircirtiom the cradie: or rank: and: ar tn be tested. being shown, out of. the: apparatus pmto their iJHSEItiQIL 2 is: a. transverse; vertical sectional: View on amerdamged scnlestazkem thmughzthe apparatus;

Bin. 3 is diagram tbs manner in which the various parts of the electrical-amaze trains are: interconnected;

Fig.3 4- is or vertical: sectimral; View takemsnbsiam fliarl-lw the 4-4 or. Eiga. 2: in the. dimention of: the; arrows; and.

Fig. 5' is a plan sectional view taken substantiarliy, along the line 5-5 ofi 2 im the: direction 015 thee arrows.

In the: drawings, as illustrated in Figs. 1,, 2, 4 and! 5 2,; fixture is provided comprising a base. tit having: side; members H. and 12': ands 8; back plate i3. linterposed betweenthe side. members is, a cover pia-te: i=4 which; extends: between: thaside memhersr in; az horicontaii plane and: abuts a rounded transparent plastic case front. ii;

which: is- 83.150- mounted. between. the, side: members and. which: its bottomand resting on at cross bar LEE. In addition to-thecrosshar l.ti,.there is a; @rossbar: L-t spaced from; the. cross, bar I61- and extending: between the side members, H and. 1'2, and: intermediate: the; cross bars L6. and: H. are. slots t8, and 1-5,. which: are,- formed; in. the. side memher-s lit and i=2; respectivzely,,to-receivenrack on cradle designated generally by thenumeral 2D to; hold mica laminations 2| in position to be tester-t: inthe apparatus. Extending between the. sidememhers I l and l2. is; a. block- I-ZJ, of; insulating material: having at parinofo contact springs 2 2: and- 23; mounted on: it for contacting with a: portion of the rack 20.

The iaminations to.- be tested in the apparatus comprise; strips or, mica Z'L, on. opposite. surfaces: at which... silver. sheets or plates 24 and-V25. have; been fixed. These laminations are placed on whiie the; rack; is out oi the.v testing fixture; midi a1 groups of: the lamination s may thus, be: fiestedtsiinultaneouslm by: inserting: the rack holding them; in the; appatrazlnzs.

Extending across: the base; Iii: between the side members: ME and t2; is. or support-block.- 311? having a; switch his of the hype known as a. microswitch mount-ow upon its. front face. Thesup? port block 3!! has a hinge 3:2 attachedto; it and to:- a mounting block 33! made off insulating martea-nd-supporting' a; plurality ofneon lamps 34'. In: addition tosupportingthe neon lamps- 34, the mounting block 33carries a series ofleafsprings 35, of whiohthere is provided one for each 1ami'nation supporting section of the rank 2!). These Ieaf springs are connectedto theneon lamps (N and constitute contact memb as for interconnecti'ng the'upper siiver sheet or-pl'ate- 2 i and the'lamp 3'4 in the ciicuit during the testing of the, lamina.- tions. The switch 3! serves. to close themain switch of the testing circuit when the mounting; bTock 23 is rocked to the, positionshown in Fig, 2; which movement will.v carry the contact springs into engagement with. the. laminations and close the switch; 31-. The, mounting. block 3.3 is. provided with a pair: of handles 35. which extend through arcuaite slots 3FE3J. formed in. the side members it and [-2 to permit the rockin oi the mounting, plate: 3-2 and parts carried thereby from the; positionshowninliig. 1 to-the position shown Fig; 2;, Any suitable; means, may be provided tor either: urging the mounting block 33 to-the, position shown Fig. 1, or for resisting. move ment of the; handles 3% throughout; their entire monuments so, that, the handles. may be moved to to the testing apparatus upon the closure of the switch 3|.

The rack or cradle comprises a main,block,

nations from slipping off the back end of the rack. A series of slots 41-41 are formed in the block 45 to receive spacers 48, which are held in place on the main block 45 by means of pins 49 inserted in the apertures in the spacers 48 and resting against the bottoms of slots 50 and 5|, which extend longitudinally of the main block 45.

In the preferred embodiment of the invention, there are ten lamination-receiving sections formed on the rack and, therefore, there are H slots 4'1 cut in the block. To conserve space, only five of the sections have been shown and the figures of the drawing have been broken through the middle to indicate the fact that a number of positions are omitted. Any suitable number of laminations may be tested at one time, but it has been found advisable to test just ten of them at a time.

The main block 45 has a series of contact members55mounted thereon. These contact members comprise a head portion 56, as shown most clearly in Fig. 2, and a shank '51, which is threaded to receive a machine screw 58. The machine screws 55 are seated in a conductor plate 59, which extends across beneath all of the lamination supporting sections of the rack and when the rack is positioned in the apparatus, the conductor plate will rest upon the contact springs 22 and 23, thus to connect the silver plate 25 on the lamination 2| in each section of the rack with the testing circuit.

As shown in Fig. 3, the laminations 2| to be tested will thus be connected in parallel across a circuit from a transformer 62, which is supplied with power from 115 volt A. C. source t3 upon closure of the switch 3| and which will apply a thousand volts through an adjustable resistance 64 and a condenser 65 to the parallel circuits in which the laminations 2| are connected by means of the contact springs 22 and 23 and contact springs 35. Each of the circuits leading from the contact springs 35 is connected directly to one of the neon lamps 34 and thence through a 90,000 ohm resistor 66 and back to the output side of the transformer 62. Connected in series with each of the 90,000 ohm resistances is a 10,000 ohm resistance 61 and the neon lamp is connected in shunt across the 10,000 ohm resistance. In the operation of the apparatus, ten laminations 2! having silver plated sheets, as shown at 24 and 25, may be placed on the rack and the rack may then be slid in position as shown in Fig. 2, where each lamination to be tested will be aligned with the contact spring fixed on the support block 33. The handles 36 may then be moved from the position shown in Fig. l to the position shown in Fig. 2. When the handles are thus moved to operative position, the switch 4 3| will be closed to supply power to the testing circuit and since the neon lamp 40 is connected across the I I0 volt source 63, closure of the switch 31 will complete the circuit to lamp to indicate that power is being supplied through the transformer 62 to the underside of all of the laminations 2! which have their silver plate 25 in engagement with one of the contact members 55. The breakdown circuit across the laminations will be completed by the contacting of the contact springs 35 with the plate 24 on the upper surface of the laminations and if none of the laminations break down under the test, none of the lamps 34 will be lighted. However, if one of the laminations being tested breaks down upon the application thereto of the 1000 volt testing current, its

associatedneon lamp 34 will be lighted. The

lighting of a neon lamp 34 due to the breaking down of the laminationzl associated therewith will not disturb the test circuits to other laminations being tested simultaneously, due to the fact that the neon lamp'34 is connected in shunt across a 10,000 ohm resistance which is, together with the lamp 34, in series with the 90,000 ohm resistance individual to it. In this manner, the application of the test to those laminations which are satisfactory will not be interfered with by the breaking down of one of the laminations since the total current of all the parallel circuits at breakdown will not be great enough to reduce the voltage belowthe minimum desired.

What is claimed is:

In a breakdown-testing apparatus, a rack for holding a pluralityof specimens to be tested, a fixture for receiving said rack, means on said rack for contacting one side of each of the specimens, a hinged frame, a plurality of neon lamps on said frame, contact fingers on said frame for interconnecting the specimens separately in series with the lamps, a resistance in series with each of said lamps,resistances individual to and in shunt with said lamps, and means for connecting said means on said rack and said resistances to a-source of high potential to supply a high voltage to all of the specimens.

2. In a breakdown testing apparatus, a rack for holding a plurality of specimens to be tested, a fixturefor receiving said rack, means on said rack for contacting one side of each of the specimens, a hinged frame, a plurality of neon lamps on said frame, contact fingers on said frame for interconnecting the specimens separately in series with the lamps, a resistance in series with each of said lamps, resistances individual to and in shunt with said lamps, means for actuating the hinged frame to engage all of the contact fingers simultaneously with their associated specimens and means for'connecting said means on said rack and said resistances to a source of high potential for supplying a high voltage to all of the specimens.

3. In a breakdown testing apparatus, a rack for holding a plurality of specimens to be tested, a fixture for receiving said rack, means on said rack for contacting one side of each of the specimens, a hinged frame, a plurality of neon lamps on said frame, contact fingers on said frame for interconnecting the specimens separately in series with the lamps, a resistance in series with each of said lamps, resistances individual to and in shunt with said lamps, and a source of power connectible to supply current in parallel to all of the specimens through the means contacting one side of the specimen and through the contact fingers.

4. In a breakdown testing apparatus, a rack for holding a plurality of specimens to be tested, a fixture for receiving said rack, means on said rack for contacting one side of each of the specimens, a hinged frame, a plurality of neon lamps on said frame, contact fingers on said frame for interconnecting the specimens separately in series with the lamps, a resistance in series with each of said lamps, resistances individual to and in shunt with said lamps, a source of power connectible to supply current in parallel to all of the specimens through the means contacting one side of the specimen and through the contact fingers, and a switch operable by the hinged frame for closing the circuit to the power source.

LEON V. MICHAL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS